1. Field of the Invention
This invention relates to water dispersible granules (WDG) of agriculturally active chemicals, and, more particularly, to free-flowing, non-dusting WDGs of water-insoluble, hydrophobic agriculturally active chemicals, which have low granule friability and superior crush strength, and which form stable, non-foaming suspensions in water, for delivery of such chemicals to a desired site.
2. Description of the Prior Art
WDGs are important delivery vehicles for active agricultural chemicals because, unlike emulsion concentrates, they are organic solvent-free, do not have dusting problems present with wettable powders, and can be transported more economically than suspension concentrates. WDGs are prepared by water-bonding particles of the active component. However, in the absence of a binder additive in the system, the granules will gradually lose cohesiveness as the water content is reduced by evaporation. A useful binder additive, therefore, must provide for effective granular crush strength and low friability, while enabling the granules to form stable suspensions in water during use, without deleterious foaming as a result thereof, and to quickly dissipate its binding action when immersed in water.
Ligninsulfonate has been considered the binder of choice in WDG systems. Polyvinylpyrrolidone, in combination with urea, has been suggested for the same use (Canadian Patent 1,209,363).
However, there is a need for new and improved WDG systems in which a combination of components therein will provide free-flowing, non-dusting granules having low granule friability and superior crush strength, and which will form stable suspensions in water without deleterious foaming. In particular, it is desired to provide for effective delivery of water-insoluble, hydrophobic agriculturally active chemicals to a desired site for application of a rainfast film on the infected plant.